val can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: vers/hwmon/nct6775.c:2698 store_pwm_weight_temp_sel() warn: potential spectre issue 'data->temp_src' [r] Fix this by sanitizing val before using it to index data->temp_src Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Unified · Split
| @@ -63,6 +63,7 @@ · 62 unmodified lines | |||
| 63 | #include <linux/bitops.h> | 63 | #include <linux/bitops.h> |
| 64 | #include <linux/dmi.h> | 64 | #include <linux/dmi.h> |
| 65 | #include <linux/io.h> | 65 | #include <linux/io.h> |
| 66 | #include <linux/nospec.h> | ||
| 66 | #include "lm75.h" | 67 | #include "lm75.h" |
| 67 | 68 | ||
| 68 | #define USE_ALTERNATE | 69 | #define USE_ALTERNATE |
| @@ -2689,6 +2690,7 @@ store_pwm_weight_temp_sel(struct device *dev, struct device_attribute *attr, · 2620 unmodified lines | |||
| 2689 | return err; | 2690 | return err; |
| 2690 | if (val > NUM_TEMP) | 2691 | if (val > NUM_TEMP) |
| 2691 | return -EINVAL; | 2692 | return -EINVAL; |
| 2693 | val = array_index_nospec(val, NUM_TEMP + 1); | ||
| 2692 | if (val && (!(data->have_temp & BIT(val - 1)) || | 2694 | if (val && (!(data->have_temp & BIT(val - 1)) || |
| 2693 | !data->temp_src[val - 1])) | 2695 | !data->temp_src[val - 1])) |
| 2694 | return -EINVAL; | 2696 | return -EINVAL; |